In this proposal, I will investigate the molecular and biochemical mechanisms of autosomal dominant progressive external opthalmoplegia (adPEO) with mitochondrial DMA multiple deletions, which is caused by mutations in the adenine nucleotide translocator (ANT) 1. Because ANT transports ADP and ATP across the mitochondrial inner membrane, it is a key player in ATP production and energy metabolism. ANT is also implicated in apoptosis initiated in mitochondria. Although the genetic causes of ANT1 adPEO are known, its pathogenic mechanisms remain undetermined. Mitochondrial abnormalities resulting from mutant ANT1 have been reported in yeast models. However, such abnormalities have not yet been studied in mammalian systems because ANT1 expression leads to apoptosis in most cultured mammalian cell types. In this study, pathogenic ANT1 mutations will be expressed in disease-pertinent skeletal and heart myocytes. Preliminary studies show that expression of ANT1 using adenoviral vectors in myocyte cultures is feasible without causing overt cell death. To investigate the pathogenesis of ANT1 adPEO I will determine the effects of ANT1 mutations on ANT function and structure, mitochondrial bioenergetics, mitochondrial DNA stability, and apoptosis, in muscle cells. [unreadable] [unreadable]